Terminal blocks commonly have one or more circuit connectors. In case of a terminal block serving as a plug-in receptacle, the connector includes an electrical conductor having a wire-fastening terminal at one end and its opposite end is formed to act as a plug-in contact. Other terminal blocks include wire-fastening terminals at the opposite ends of a conductor. Commonly screws or screw-operated clamps are used as the wire fasteners. The present invention has various novel aspects that apply to terminal blocks having circuit connectors bearing two wire fasteners and to plug-in terminal blocks and plug-in units. This invention also has features applicable to plug-in connectors in particular, comprising a plug-in terminal block and a companion plug-in unit.
It has been proposed that terminal blocks having terminal screws (including binding-head screws, clamp-actuating screws and others) should be disposed for easy access where a first panel supports a terminal block and another panel is placed opposite the first so close to allow only a small space between the panels. As one step in meeting this requirement of limited access, it has been proposed that the terminal screws should be directed parallel to or at a small angle to the panel that supports a terminal block. It has also been proposed that the terminal block should be mounted in an opening in the panel, arranged to make circuit connections extending through the panel opening. In that case, the terminal block is to have a shoulder engaging an edge of the panel opening, and the terminal screw (or a row or rows of screws) advantageously is to be arranged on an insulating body so that screw-driver thrust against the screw(s) is directed at least approximately at the shoulder that bears against the panel opening. This arrangement avoids imposing screw-driver thrust against the terminal block in a way that would stress whatever means is provided for holding the terminal block assembled to the panel.